This operation create a new UTO object representing the time in the target
object added to current time (UTC). The time base is
15 october 1582 00:00. Comparing two time objects which use
different time base is, by obvious reasons, pointless.
Raises DATA_CONVERSION if causes an overflow. This operation is only useful
if the target object represents a relative time.

This operation compares the time associated with the target object and the
given UTO object. The different ComparisonType are:

'MidC' - only compare the time represented by each object. Furthermore,
the target object is always used as the first parameter in the
comparison, i.e., if the target object's time is larger
'TCGreaterThan' will be returned.

'IntervalC' - also takes the inaccuracy into consideration, i.e.,
if the two objects interval overlaps 'TCIndeterminate' is returned,
otherwise the as for 'MidC'.

This operation creates a TIO object representing the error interval
around the time value represented by the target object, i.e.,
TIO.upper_bound = UTO.time+UTO.inaccuracy and
TIO.lower_bound = UTO.time-UTO.inaccuracy.